Medical rinsing systems are used widely in surgery to clean tissue areas. Said rinsing systems are called lavage systems. The lavage systems and rinsing liquids are used to produce spray jets that impinge on the tissue areas to be cleaned and exert a mechanical cleaning effect on said tissue areas. Specifically during the implantation of articular endoprostheses and during septic revisions, lavage systems have essential significance (R. M. Sherman et al.: The role of lavage in preventing hemodynamic and blood-gas changes during cemented arthroplasty. J. Bone Joint. Surg. 1983; 65-A: 500-506; S. J. Breusch et al.: Zementierte Hüftendoprothetik: Verminderung des Fettembolierisikos in der zementierten Hüftendoprothetik mittels gepulster Druckspülung. Orthopädie 2000; 29: 578-586; S. J. Breusch et al.: Lavage technique in THA: Jet-lavage Produces Better Cement Penetration Than Syringe-Lavage in the Proximal Femur. J. Arthroplasty. 200; 15(7): 921-927; R. J. Byrick et al.: High-volume, high pressure pulsatile lavage during cemented arthroplasty. J. Bone Joint Surg. 1989; 81-A: 1331-1336; J. Christie et al.: Medullary lavage reduces embolic phenomena and cardiopulmonary changes during cemented hemiarthroplasty. J. Bone Joint Surg. 1995; 77-B: 456-459).
Pulsed lavage systems have been known for a long time, for example from U.S. Pat. No. 4,583,531 A, U.S. Pat. No. 4,278,078 A, and U.S. Pat. No. 5,542,918 A. The lavage systems currently on the market are driven by means of electrical motors (for example InterPulse® Jet lavage made by Stryker GmbH & Co. KG) or compressed air (for example PALAVAGE® made by Heraeus Medical GmbH). Hand-held, electrically-driven lavage systems have also proven useful. However, a large battery block or rechargeable battery block, which only has a limited charge capacity due to its nature, always needs to be taken along. Battery blocks and rechargeable battery blocks are viewed critically in terms of their environmental impact. Compressed gas-driven lavage systems are advantageous in that compressed air is usually available in the operating theatre in unlimited quantities and thus allows rinsing liquid to be sprayed for any desired time without the energy supply being limited.
However, using compressed air-driven lavage systems requires the use of a two-tube system, in which the non-sterile compressed air is supplied through one tube and a second tube is used to discharge the non-sterile air, which is partially expanded after it drives the compressed air motor. However, systems driven by compressed air or any other compressed gas usually utilise a compressed gas motor as the drive. Most compressed gas motors for lavage systems are lamellar compressed gas motors. The compressed gas motor generates a rotary motion which is then translated into an oscillating linear motion. The oscillating linear motion is utilised to convey momentum to small volumes of the rinsing medium. It is common in this context to arrange at least one membrane between the drive and the inlet of rinsing liquid in order to be able to transmit the pulses to the rinsing liquid. This generates spray puffs at high pulse rates of 2,000 to 3,000 pulses per minute. This means that the compressed gas motor needs to be manufactured at high precision in order to tolerate such high rotation rates. Moreover, sufficiently stable storage must be available. For these reasons, the compressed gas motor is the most expensive component of common compressed air-driven lavage systems. Therefore, the compressed gas motor is generally arranged in a handle made of metal or other durable materials such that this component can be used multiply after appropriate reprocessing and sterilisation. Compressed gas motors utilise the pressure difference between the compressed gas used to drive the motor and the pressure of the ambient atmosphere. Theoretically, they could also be operated by means of a negative pressure applied to the gas outlet, since it is just the pressure difference that is important in this context.
A compressed gas motor is known from DE 10 2010 046 057 B3, in which a plunger system generates a periodical motion that can also be used to pump liquids.
A proposal related to the generation of pulsed liquid jets is described in DE 10 2011 018 708 A1. In this context, a plunger vibrator acts periodically on a membrane. The membrane and a hollow space jointly form a pump.
However, one disadvantage of all pumps with a membrane is that it is very difficult to manufacture a suitable membrane with a high restoring force that can follow the high pulse rates of a plunger vibrator and/or vibration body. As a result, high pulse rates can be implemented only with great effort. Moreover, said systems are sensitive due to the axial deformability of the membrane, since the vibration body can move too far axially into the direction of the membrane and thus might come to a standstill. Said systems are not sufficiently robust.
Other compressed gas motors can get locked by the plungers lodging and thus locking. Moreover, the plungers might take on a position, in which the compressed gas motor does not restart by itself without further ado.
Compressed gas motors are well-suited not only for lavage systems, but can also be used in all applications, in which a compressed gas is available and an inexpensive drive is advantageous. Said requirements are evident, for example, in shaker facilities, in which bulk goods or powder need(s) to be transported, filled into containers and/or dosed. Likewise, said compressed gas motors can be used to advantage as pumps providing lubricants.
Accordingly, it is the object of the invention to overcome the disadvantages of the prior art. Specifically, the object is to discover an inexpensive and reliable compressed gas motor that can be used for the afore-mentioned purposes. The invention is therefore based on the object to develop a robust, maximally simplified medical rinsing device that can generate a pulsed liquid jet, whereby the pulse rate shall exceed, in particular, 1,000 pulses per minute. It shall be feasible to manufacture the device largely from inexpensive materials and to drive the device by compressed gas. The medical rinsing device to be developed can be intended for single use. The rinsing device shall be well-suited for operation with compressed air from stationary compressed air supply systems and for operation with compressed gases from mobile compressed gas bottles or gas cartridges.
It is an object of the invention to develop a maximally simplified plunger-equipped compressed gas motor that can generate a periodical linear plunger motion. It shall be feasible to operate the compressed gas motor with the compressed gas from stationary compressed gas facilities that are common in hospitals. Moreover, a method for generating a linear periodical motion is to be developed, in which the compressed gas motor to be developed is to be used or at least is usable. It is important in this context that the compressed gas motor works without complex costly valve systems and is simplified to the extent that as many components of the compressed gas motor as possible can be produced inexpensively through injection moulding of plastic materials or by turning of easily processing metal bodies. The compressed gas motor shall be usable to drive a medical rinsing device. Valve systems that take up a large volume and need to be positioned separately from the compressed gas motor need to be avoided. Accordingly, the requisite valve functions shall be integrated into the compressed gas motor in space-saving manner in order to enable the use of the compressed gas motor as a drive in hand-pieces of lavage systems. Ideally, the time control of the valve functions should be implemented appropriately such that there is no “dead centre” at any point of the plunger motion. Moreover, a simplified pump for integration into hand-held lavage systems is to be developed along with the compressed gas motor. A pump driven by the compressed gas motor shall be simplified to the extent that it can be manufactured inexpensively enough to also allow it to be used in lavage systems intended for single use only.